Fe-MnO_x催化臭氧氧化甲基橙

Ozonation of Methyl Orange Catalyzed by Fe-MnO_x

实验以甲基橙为目标物,考察Fe-Mn Ox的催化效果,同时比较不同煅烧温度(300、400、500、600和700℃)、Fe/Mn混合比例(n(Fe)∶n(Mn)=1∶3、n(Fe)∶n(Mn)=1∶1和n(Fe)∶n(Mn)=3∶1)等制备条件对催化剂活性的影响,力求得到催化剂的最佳制备条件。结果表明:在400°C,n(Fe)∶n(Mn)=1∶1的制备条件下,Fe-Mn Ox催化剂对催化臭氧降解甲基橙表现出显著的催化活性,反应进行20 min后,甲基橙的去除率高达70.26%,较单独臭氧氧化提高了32.29%;加入叔丁醇(TBA)后,明显抑制甲基橙去除率,说明催化过程不仅存在羟基自由基反应机理,而且存在臭氧分子与吸附在催化剂表面的甲基橙直接反应的反应途径。为了进一步了解催化剂的催化活性和内部结构之间的内在关系,采用XPS、XRD、TEM和BET等检测技术对催化活性最好的Fe-Mn Ox催化剂进行表征。表征的结果显示:Fe-Mn Ox催化剂中存在Fe2O3、Fe O(OH)、Mn O2和Mn5O8,且催化剂结构呈不定晶型,结构疏散,表面孔隙多,比表面积高达117.81 m2/g。

Methyl Orange was used as target for exploring the catalytic ability of Fe- Mn Ox. In the experiment,the factors of calcination temperature and doping ratio of Fe∶ Mn were studied to determine the optimal catalyst preparation condition. The Fe- Mn Oxwith the highest catalytic ability was characterized by XPS,XRD,SEM and BET. The result showed that Fe- Mn Ox,prepared under the conditions of 400 ℃ calcination temperature and n( Fe) ∶ n( Mn) = 1 ∶ 1,exhibited the highest catalytic,after 20 min reaction,the degradation of methyl orange was 70. 26%,which increased by 32. 29% compared with that in the sole ozonation. With the addition of Tert-butano( TBA),the degradation of methyl orange was inhibited partly,which indicated that the reaction mechanism not only involved of the hydroxyl radical reaction mechanism,but also other reaction mechanism. In order to further understand the intrinsic relationship between catalytic activity and internal structure of the catalyst,the Fe- Mn Oxwith best catalytic activity was characterized by XPS,TEM,XRD and BET,which indicated that the Fe- Mn Oxconsisted of Fe2O3,Fe O( OH),Mn O2 and Mn5O8. Besides,the catalyst was in uncertain crystal and evacuated structure,corresponding to an big specific surface area of 117. 81 m2/ g.